Safari_ deletes all bookmarks once updated

I find VERY disappointing the fact that almost every time Safarai updates, all bookmarks are removed.

I already faced this situation twice within half a year.

I use bookmarks on websites I do not want to remember the address, but for which I'd like to come back visit again. Unfortunately, they're all gone again today...

I hope Apple can find a smart way to do those updates without having any effect on this aspect.